zephyr/samples/philosophers
Anas Nashif 2bc9d69981 build: abstract emulation and replace qemu goal with run
This will replace the current goal of 'make qemu' with 'make run' and
moves Qemu handling into its own file and into the boards instead of
being architecture specific.

We should be able to add new boards that support some other type of
emulation (by adding scripts/Makefile.<emu type>) and allow the board to
define their own options for the use type of emulation.

'make qemu' will still work, however it will be deprecated, starting
with this commit it is recommended to use 'make run'.

Jira: ZEP-359
Change-Id: I1cacd56b4ec09421a58cf5d010e22e9035214df6
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
2017-01-10 20:20:47 +00:00
..
src samples: put philosophers stacks in noinit section 2017-01-06 17:38:21 +00:00
Makefile samples: tests: remove obsolete KERNEL_TYPE and kernel variables 2016-11-04 15:47:25 -04:00
prj.conf samples: configure philosophers with more than 32 priorities 2016-11-18 23:45:35 +00:00
README.rst build: abstract emulation and replace qemu goal with run 2017-01-10 20:20:47 +00:00

Dining Philosophers
###################

Overview
========

An implementation of a solution to the Dining Philosophers problem (a classic
multi-thread synchronization problem).  This particular implementation
demonstrates the usage of multiple preemptible and cooperative threads of
differing priorities, as well as dynamic mutexes and thread sleeping.

The philosopher always tries to get the lowest fork first (f1 then f2).  When
done, he will give back the forks in the reverse order (f2 then f1).  If he
gets two forks, he is EATING.  Otherwise, he is THINKING. Transitional states
are shown as well, such as STARVING when the philosopher is hungry but the
forks are not available, and HOLDING ONE FORK when a philosopher is waiting
for the second fork to be available.

Each Philosopher will randomly alternate between the EATING and THINKING state.

Building and Running
====================

This project outputs to the console.  It can be built and executed
on QEMU as follows:

.. code-block:: console

   $ cd samples/philosophers
   $ make run

Sample Output
-------------

.. code-block:: console

   Philosopher 0 [P: 3]  HOLDING ONE FORK
   Philosopher 1 [P: 2]  HOLDING ONE FORK
   Philosopher 2 [P: 1]  EATING  [ 1900 ms ]
   Philosopher 3 [P: 0]  THINKING [ 2500 ms ]
   Philosopher 4 [C:-1]  THINKING [ 2200 ms ]
   Philosopher 5 [C:-2]  THINKING [ 1700 ms ]